Electrical Power Generation – 2140908

Active Learning Assignment

“Topics”

Diesel Power Station

Guided By: Prof. Rahil sir

Branch : Electrical Engineering

Div: B

Batch : B1

Presented by:

Het amin-130120109002

Abdul chhipa-130120109005

Shah harshil-130120109012

DIESEL ENGINE POWER PLANT

CHEMICAL

ENERGYMECHENICAL

ENERGYELECTRICAL

ENERGY

FUEL

(DIESEL)

DIESEL

ENGINEALTERNATOR

R

YB

INTRODUCTION

For generating electrical power, it is essential to rotate the rotor of an alternator by means of a

prime mover. The prime mover can be driven by different methods. Using diesel engine as

prime mover is one of the popular methods of generating power. When prime mover of the

alternators is diesel engine, the power station is called diesel power station.

SCHEMATIC ARRAINGEMENT OF DIESEL

POWER STATION

Fuel Supply SystemIn fuel supply system there are one storage tank, where oil in stored.

Strainer : This oil then pump to dry tank, by means of transfer pump.

During transferring from main tank to smaller dry tank, the oil passes through strainer to remove solid impurities. From dry tank to main tank, there is another pipe connection. This is over flow pipe. This pipe connection is used to return the oil from dry tank to main tank in the event of over flowing.

From dry tank the oil is injected in the diesel engine by means of fuel injection pump.

Air Intake SystemThis system supplies necessary air to the engine for fuel combustion. It consists of

a pipe for supplying of fresh air to the engine. Filters are provided to remove dust

particles from air.

Exhaust SystemThe exhaust gas is removed from engine, to the atmosphere by means of an

exhaust system. A silencer is normally used in this system to reduce noise level of

the engine.

Cooling SystemThe heat produced due to internal combustion, drives the engine. But some parts of this

heat raise the temperature of different parts of the engine. High temperature may cause

permanent damage to the machine. Hence, it is essential to maintain the overall

temperature of the engine to a tolerable level. Cooling system of diesel power station

does exactly so. The cooling system requires a water source, water source, water pump

and cooling towers. The pump circulates water through cylinder and head jacket. The

water takes away heat from the engine and it becomes hot. The hot water is cooled by

cooling towers and is re-circulated for cooling.

Lubricating SystemThis system minimizes the water of rubbing surface of the engine. Here

lubricating oil is stored in main lubricating oil tank. This lubricating oil is drawn

from the tank by means of oil pump. Then the oil is passed through the oil filter

for removing impurities. From the filtering point, this clean lubricating oil is

delivered to the different points of the machine where lubrication is required the

oil cooler is provided in the system to keep the temperature of the lubricating oil

as low as possible.

Starting SystemFor starting a diesel engine, initial rotation of the engine shaft is required. Until

the firing start and the unit runs with its own power. For small DG set, the initial

rotation of the shaft is provided by handles but for large diesel power station.

Compressed air is made for starting.

APPLICATION OF DIESEL POWER

STATION They are used as central station for small or medium power supplies.

They can be used as stand-by plants to hydro-electric power plants and steam power

plants for emergency services.

They can be used as peak load plants in combinations with thermal or hydro-plants.

They are quite suitable for mobile power generation and are widely used in

transportation systems such as automobiles, railways, air planes and ships.

Now-a-days power cut has become a regular feature for industries. The only solution

to tide over this difficulty is to install diesel generating sets.

DISADVANTAGES

High running charges due

to costly price of Diesel

Generates small amount of

power

Cost of lubrication very

high

Maintenance charges are

generally high

ADVANTAGES AND DISADVANTAGES OF

DIESEL POWER PLANT

ADVANTAGE

Simple design & layout of plant

Occupies less space & is compact

Can be started quickly and picks

up load in a short time

Requires less water for cooling

Thermal efficiency better that of

Steam Power Plant of same size

Overall cost is cheaper than that of

Steam Power Plant of same size

GENERAL LAYOUT

ENGINE DETAILS

CYLINDER It is the heart of the engine in which the fuel is burnt and the power is developed.

Cylinder has to withstand very high pressure and temperature because the combustion of fuel

is carried out within the cylinder so it must be cooled.

The inside diameter is called bore.

Cylinder head

Cylinder head covers top end of cylinder.

Valve mechanism, spark plug, fuel injector etc are placed on cylinder head.

Piston

The piston is a close fitting hollow cylindrical plunger reciprocating inside the cylinder.

The power developed by the combustion of fuel is transmitted by piston to the crank shaft through connecting rod.

Piston rings and pin

The piston rings are the metallic rings inserted into the circumferential grooves provided at the top end of the piston.

Piston ring is also known as gudgeon pin

It is pin joining small and of the connecting rod and piston and it is made of

steel.

Connecting rod It is the member connecting piston through piston pin and crank shaft

through crank pin.

It converts the reciprocating motion of the piston in to rotary motion of

crank shaft

Crank and crankshaft

The crank is a lever that is connected to the big end of the connecting rod

by a pin joint with its other end connected to shaft which called crankshaft.

Valves and fly wheels Engine has both intake and exhaust type of valves which are operated by valve

operating mechanism

Fly wheel is a heavy wheel mounted on the crankshaft of the engine and it minimize cyclic variation during the stroke

Crankcase and fuel pump and injector Crank case is the lower part of the engine serving as an enclosure of the

crankshaft

Fuel pump is used in diesel engine for increasing pressure and injector is used to inject diesel fuel in the form of spray under pressure.

Working of Two stroke

Diesel Engine

The construction of diesel engine is similar to two stroke petrol engine except the fuel pump and fuel injector are there instead of carburetor and sparkplug.

It consist two stroke in the cycle.

First stroke

At the beginning of the first stroke, the piston is at TDC and then moves to BDC. At TDC piston is at the end of compression, so the compressed air will attain a temperature higher than self ignition temperature of the diesel

The injector injects a metered quantity of the diesel into the cylinder as a fine spray. As diesel is injected it auto ignites.

The combustion of the diesel will release the hot gases which increases the pressure and temperate in the cylinder

Second stroke

In this stroke the piston moves from TDC to BDC. When it covers the

transfer port, the supply of air is stop and when it moves further up it

covers the exhaust port completely stops the scavenging

Further upward motion of the piston will compress the air in the cylinder

After the piston reaches TDC the first stroke repeats again

Suction strokeDuring this stroke, inlet valve opens and exhaust valve is closed, the pressure in the cylinder will be atmospheric. As the piston moves from TDC to BDC, the volume in the cylinder increases, while simultaneously the pressure decreases.

This creates a pressure difference between the atmosphere and inside of the cylinder.

Due to this pressure difference only the atmospheric air will enter into the cylinder through air filter and inlet.

At the end of this stroke, the cylinder will be filled completely with air and inlet valve will be closed

Working of Four stroke Diesel Engine

Compression stroke

During this stroke, both inlet valve andexhaust valve remain closed. The pistonmoves from BDC to TDC. As this strokeis being performed, the air in the cylinderwill be compressed, so pressure andtemperature of air increases.

The compression ratio of this engine ishigher than petrol engine. Due to highercompression ratio, air will have attained ahigher temperature than self ignitiontemperature of diesel fuel.

A metered quantity of the diesel fuel isinjected into the cylinder. As the dieselfuel particles come in contact with hightemperature it will ignite automatically.This is called self ignition

Power stroke

During this stroke, both the inlet valve and the exhaust valve are closed. The piston moves from TDC to BDC.

The fuel injection starts nearly at the end of compression stroke, but the rate of fuel injection is such that combustion maintains constant pressure.

This piston is forced further during the remaining part of this stroke only due to the expansion of the burnt gases. The engine produce mechanical work in this stroke

Exhaust stroke

During this stroke , the exhaust

valve opens and inlet valve is

closed. The piston moves TDC to

BDC.

During this motion, piston pushes

the exhaust gases out of cylinder at

constant pressure.